The act of being extremely hungry while in a state of intoxication, where getting to McDonalds seems like a "do or die" situation. No other food will suffice unless it is from McDonalds. The agent may do questionable things to get to a McDonalds, or perform extreme actions in order to acquire a meal from McDonalds.

Man I was so bombed last night and I had the worst McMunchies, I took a $55 cab just to get there. Haven't had McMunchies that bad in a while.